Writing unit tests is a nice way to work when you're not working in an environment that requires young goat sacrifices or some such thing to perform unit tests.

Writing unit tests is a nice way to work when you're not working in an environment that requires young goat sacrifices or some such thing to perform unit tests. I'd also say that some kinds of unit tests are also a limited form of documentation. They don't tell you why something works the way it does, but they do tell you how it works.